High level conclusions

Fuzzers reach 95.75% code coverage.

Fuzzers reach 71.62% of cyclomatic complexity.

Fuzzers reach 75.47% of all functions.

Reachability and coverage overview

Functions statically reachable by fuzzers

160 / 212

Cyclomatic complexity statically reachable by fuzzers

2204 / 3077

Runtime code coverage of functions

203 / 212

Warning: The number of runtime covered functions are larger than the number of reachable functions. This means that Fuzz Introspector found there are more functions covered at runtime than what is considered reachable based on the static analysis. This is a limitation in the analysis as anything covered at runtime is by definition reachable by the fuzzers.
This is likely due to a limitation in the static analysis. In this case, the count of functions covered at runtime is the true value, which means this is what should be considered "achieved" by the fuzzer.

Use the project functions table below to query all functions that were not covered at runtime.

The following table shows data about each function in the project. The functions included in this table correspond to all functions that exist in the executables of the fuzzers. As such, there may be functions that are from third-party libraries.

For further technical details on the meaning of columns in the below table, please see the Glossary .

Func name	Functions filename	Args	Function call depth	Reached by Fuzzers	Runtime reached by Fuzzers	Combined reached by Fuzzers	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

Fuzzer: ZydisFuzzReEncoding

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	138	17.8%
gold	[1:9]	47	6.07%
yellow	[10:29]	68	8.78%
greenyellow	[30:49]	26	3.35%
lawngreen	50+	495	63.9%
All colors	774	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
12	737	ZydisValidateInstructionIdentity	call site: 00737	fprintf
8	727	ZydisReEncodeInstruction	call site: 00727	fputs
7	216	ZydisSetAVXInformation	call site: 00216	__assert_fail
4	128	ZydisNodeHandlerRexB	call site: 00128	__assert_fail
4	344	ZydisSetOperandSizeAndElementInfo	call site: 00344	__assert_fail
3	47	ZydisDecodeModRM	call site: 00047	__assert_fail
3	159	ZydisSetAttributes	call site: 00159	__assert_fail
3	296	ZydisDecodeOperands	call site: 00296	ZydisDecodeOperandRegister
3	433	ZydisReEncodeInstruction	call site: 00433	__assert_fail
3	462	ZydisIsBroadcastModeCompatible	call site: 00462	__assert_fail
3	582	ZydisGetEffectiveImmSize	call site: 00582	__assert_fail
3	596	ZydisIsImmediateOperandCompabile	call site: 00596	__assert_fail

Runtime coverage analysis

Covered functions

146

Functions that are reachable but not covered

5

Reachable functions

148

Percentage of reachable functions covered

96.62%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
build/../tools/ZydisFuzzShared.c	7
build/../tools/ZydisFuzzReEncoding.c	1
src/Decoder.c	59
src/DecoderData.c	2
src/SharedData.c	6
src/Register.c	5
src/Encoder.c	59
src/EncoderData.c	1
src/Generated/GetCcInfo.inc	1
src/Utils.c	1
src/Generated/GetRelInfo.inc	1

Fuzzer: ZydisFuzzEncoder

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	161	20.0%
gold	[1:9]	31	3.87%
yellow	[10:29]	93	11.6%
greenyellow	[30:49]	26	3.24%
lawngreen	50+	490	61.1%
All colors	801	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
15	649	ZydisFuzzTarget	call site: 00649	ZydisCalcAbsoluteAddress
12	764	ZydisValidateInstructionIdentity	call site: 00764	fprintf
8	754	ZydisReEncodeInstruction	call site: 00754	fputs
7	513	ZydisSetAVXInformation	call site: 00513	__assert_fail
4	425	ZydisNodeHandlerRexB	call site: 00425	__assert_fail
4	637	ZydisSetOperandSizeAndElementInfo	call site: 00637	__assert_fail
3	30	ZydisIsBroadcastModeCompatible	call site: 00030	__assert_fail
3	107	ZydisCheckVectorMemorySize	call site: 00107	__assert_fail
3	153	ZydisGetEffectiveImmSize	call site: 00153	__assert_fail
3	167	ZydisIsImmediateOperandCompabile	call site: 00167	__assert_fail
3	456	ZydisSetAttributes	call site: 00456	__assert_fail
3	591	ZydisDecodeOperands	call site: 00591	ZydisDecodeOperandRegister

Runtime coverage analysis

Covered functions

147

Functions that are reachable but not covered

5

Reachable functions

149

Percentage of reachable functions covered

96.64%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
build/../tools/ZydisFuzzShared.c	7
build/../tools/ZydisFuzzEncoder.c	2
src/Encoder.c	59
src/EncoderData.c	1
src/SharedData.c	6
src/Generated/GetCcInfo.inc	1
src/Register.c	5
src/Decoder.c	59
src/DecoderData.c	2
src/Utils.c	1
src/Generated/GetRelInfo.inc	1

Fuzzer: ZydisFuzzDecoder

Call tree

The calltree shows the control flow of the fuzzer. This is overlaid with coverage information to display how much of the potential code a fuzzer can reach is in fact covered at runtime. In the following there is a link to a detailed calltree visualisation as well as a bitmap showing a high-level view of the calltree. For further information about these topics please see the glossary for full calltree and calltree overview

Call tree overview bitmap:

The distribution of callsites in terms of coloring is

Color	Runtime hitcount	Callsite count	Percentage
red	0	65	14.0%
gold	[1:9]	44	9.54%
yellow	[10:29]	32	6.94%
greenyellow	[30:49]	18	3.90%
lawngreen	50+	302	65.5%
All colors	461	100

Fuzz blockers

The following nodes represent call sites where fuzz blockers occur.

Amount of callsites blocked	Calltree index	Parent function	Callsite	Largest blocked function
7	216	ZydisSetAVXInformation	call site: 00216	__assert_fail
4	128	ZydisNodeHandlerRexB	call site: 00128	__assert_fail
4	344	ZydisSetOperandSizeAndElementInfo	call site: 00344	__assert_fail
3	47	ZydisDecodeModRM	call site: 00047	__assert_fail
3	159	ZydisSetAttributes	call site: 00159	__assert_fail
3	296	ZydisDecodeOperands	call site: 00296	ZydisDecodeOperandRegister
2	104	ZydisTreeWalkFilters	call site: 00104	ZydisDecodeModRM
2	280	ZydisDecodeOperandImplicitMemory	call site: 00280	ZydisCalcRegisterId
2	385	ZydisValidateEnumRanges	call site: 00385	fprintf
1	19	ZydisNodeHandlerXOP	call site: 00019	__assert_fail
1	22	ZydisNodeHandlerVEX	call site: 00022	__assert_fail
1	26	ZydisNodeHandlerEMVEX	call site: 00026	__assert_fail

Runtime coverage analysis

Covered functions

139

Functions that are reachable but not covered

4

Reachable functions

99

Percentage of reachable functions covered

95.96%

NB: The sum of covered functions and functions that are reachable but not covered need not be equal to Reachable functions . This is because the reachability analysis is an approximation and thus at runtime some functions may be covered that are not included in the reachability analysis. This is a limitation of our static analysis capabilities.

Warning: The number of covered functions are larger than the number of reachable functions. This means that there are more functions covered at runtime than are extracted using static analysis. This is likely a result of the static analysis component failing to extract the right call graph or the coverage runtime being compiled with sanitizers in code that the static analysis has not analysed. This can happen if lto/gold is not used in all places that coverage instrumentation is used.

Function name	source code lines	source lines hit	percentage hit

Files reached

filename	functions hit
build/../tools/ZydisFuzzShared.c	4
build/../tools/ZydisFuzzDecoder.c	1
src/Decoder.c	59
src/DecoderData.c	2
src/SharedData.c	6
src/Register.c	8
src/Formatter.c	8
src/FormatterBuffer.c	2
src/Utils.c	1
src/Mnemonic.c	2
src/Segment.c	1
src/Zydis.c	1

Optimal target analysis

Remaining optimal interesting functions

The following table shows a list of functions that are optimal targets. Optimal targets are identified by finding the functions that in combination, yield a high code coverage.

Func name	Functions filename	Arg count	Args	Function depth	hitcount	instr count	bb count	cyclomatic complexity	Reachable functions	Incoming references	total cyclomatic complexity	Unreached complexity
ZydisFormatterIntelPrintDecoratorMASM	/src/zydis/src/FormatterIntel.c	4	['N/A', 'N/A', 'N/A', 'int']	3	0	54	15	4	6	0	244	242
ZydisFormatterBasePrintPrefixes	/src/zydis/src/FormatterBase.c	3	['N/A', 'N/A', 'N/A']	3	0	984	228	93	9	0	202	127
ZydisFormatterATTFormatInstruction	/src/zydis/src/FormatterATT.c	3	['N/A', 'N/A', 'N/A']	3	0	727	159	62	8	0	102	79
ZydisFormatterIntelFormatInstructionMASM	/src/zydis/src/FormatterIntel.c	3	['N/A', 'N/A', 'N/A']	4	0	38	9	2	9	0	101	61
ZydisFormatterIntelPrintTypecastMASM	/src/zydis/src/FormatterIntel.c	3	['N/A', 'N/A', 'N/A']	3	0	140	35	11	6	0	68	54
ZydisFormatterATTFormatOperandMEM	/src/zydis/src/FormatterATT.c	3	['N/A', 'N/A', 'N/A']	3	0	491	111	46	7	0	82	46
ZydisFormatterIntelFormatOperandMEM	/src/zydis/src/FormatterIntel.c	3	['N/A', 'N/A', 'N/A']	3	0	476	106	44	7	0	80	44
ZydisFormatterATTPrintIMM	/src/zydis/src/FormatterATT.c	3	['N/A', 'N/A', 'N/A']	4	0	64	17	5	14	0	98	40

Implementing fuzzers that target the above functions will improve reachability such that it becomes:

Functions statically reachable by fuzzers

188 / 212

Cyclomatic complexity statically reachable by fuzzers

2897 / 3077

All functions overview

If you implement fuzzers for these functions, the status of all functions in the project will be:

Func name	Functions filename	Args	Function call depth	Reached by Fuzzers	Runtime reached by Fuzzers	Combined reached by Fuzzers	Fuzzers runtime hit	Func lines hit %	I Count	BB Count	Cyclomatic complexity	Functions reached	Reached by functions	Accumulated cyclomatic complexity	Undiscovered complexity

This sections provides heuristics that can be used as input to a fuzz engine when running a given fuzz target. The current focus is on providing input that is usable by libFuzzer.

build/../tools/ZydisFuzzShared.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['ZydisValidateInstructionIdentity', 'ZydisReEncodeInstruction', 'ZydisSetAVXInformation', 'ZydisNodeHandlerRexB', 'ZydisSetOperandSizeAndElementInfo', 'ZydisDecodeModRM', 'ZydisSetAttributes', 'ZydisDecodeOperands', 'ZydisIsBroadcastModeCompatible']

build/../tools/ZydisFuzzShared.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['ZydisFuzzTarget', 'ZydisValidateInstructionIdentity', 'ZydisReEncodeInstruction', 'ZydisSetAVXInformation', 'ZydisNodeHandlerRexB', 'ZydisSetOperandSizeAndElementInfo', 'ZydisIsBroadcastModeCompatible', 'ZydisCheckVectorMemorySize', 'ZydisGetEffectiveImmSize', 'ZydisIsImmediateOperandCompabile']

build/../tools/ZydisFuzzShared.c

Dictionary

Use this with the libFuzzer -dict=DICT.file flag

Fuzzer function priority

Use one of these functions as input to libfuzzer with flag: -focus_function name

-focus_function=['ZydisSetAVXInformation', 'ZydisNodeHandlerRexB', 'ZydisSetOperandSizeAndElementInfo', 'ZydisDecodeModRM', 'ZydisSetAttributes', 'ZydisDecodeOperands', 'ZydisTreeWalkFilters', 'ZydisDecodeOperandImplicitMemory', 'ZydisValidateEnumRanges', 'ZydisNodeHandlerXOP']

This section shows analysis of runtime coverage data.

For futher technical details on how this section is generated, please see the Glossary .

Complex functions with low coverage

Func name	Function total lines	Lines covered at runtime	percentage covered	Reached by fuzzers
ZydisCompareRequestToInstruction	127	56	44.09%	['ZydisFuzzEncoder']

This section shows which files and directories are considered in this report. The main reason for showing this is fuzz introspector may include more code in the reasoning than is desired. This section helps identify if too many files/directories are included, e.g. third party code, which may be irrelevant for the threat model. In the event too much is included, fuzz introspector supports a configuration file that can exclude data from the report. See the following link for more information on how to create a config file: link

Files in report

Source file	Reached by	Covered by
	[]	[]
/src/zydis/src/Generated/GetRelInfo.inc	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder']	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder']
/src/zydis/build/../tools/ZydisFuzzEncoder.c	['ZydisFuzzEncoder']	[]
/src/zydis/dependencies/zycore/include/Zycore/Format.h	[]	[]
/src/zydis/src/Formatter.c	['ZydisFuzzDecoder']	['ZydisFuzzDecoder']
/src/zydis/src/Segment.c	['ZydisFuzzDecoder']	['ZydisFuzzDecoder']
/src/zydis/src/String.c	[]	[]
/src/zydis/src/FormatterBase.c	[]	[]
/src/zydis/src/FormatterATT.c	[]	[]
/src/zydis/src/FormatterIntel.c	[]	[]
/src/zydis/src/Register.c	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']
/src/zydis/include/Zydis/Internal/String.h	[]	[]
/src/zydis/build/../tools/ZydisFuzzShared.c	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']	[]
/src/zydis/src/SharedData.c	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']
/src/zydis/src/Generated/GetCcInfo.inc	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder']	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder']
/src/zydis/include/Zydis/Internal/FormatterBase.h	[]	[]
/src/zydis/src/Encoder.c	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder']	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder']
/src/zydis/src/Decoder.c	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']
/src/zydis/src/FormatterBuffer.c	['ZydisFuzzDecoder']	['ZydisFuzzDecoder']
/src/zydis/build/../tools/ZydisFuzzReEncoding.c	['ZydisFuzzReEncoding']	[]
/src/zydis/src/Mnemonic.c	['ZydisFuzzDecoder']	['ZydisFuzzDecoder']
/src/zydis/src/Utils.c	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']
/src/zydis/src/EncoderData.c	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder']	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder']
/src/zydis/src/DecoderData.c	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']	['ZydisFuzzReEncoding', 'ZydisFuzzEncoder', 'ZydisFuzzDecoder']
/src/zydis/build/../tools/ZydisFuzzDecoder.c	['ZydisFuzzDecoder']	[]
/src/zydis/src/Zydis.c	['ZydisFuzzDecoder']	['ZydisFuzzDecoder']

Directories in report

Directory
/src/zydis/src/Generated/
/src/zydis/dependencies/zycore/include/Zycore/
/src/zydis/build/../tools/
/src/zydis/include/Zydis/Internal/
/src/zydis/src/